As semiconductor devices are gradually becoming more highly-integrated, a short-channel transistor fabrication technology is required. However, a short-channel effect which reduces the effective channel length occurs due to the lateral diffusion of source/drain diffusion layer. In general, the short-channel effect reduces the amount of ion implantation in a lightly doped junction region, thus minimizing the effect thereof.
In addition, as the length of a gate electrode is shortened, a narrow line effect occurs. Since the narrow line effect disturbs the formation of salicide, the effect of disturbance is minimized in such a manner to change the type of metal layers in order to deposit a salicide film.
However, the reduction of the amount of ion implantation in a lightly doped junction region gives rise to problems such as deterioration caused by a hot carrier effect becomes more noticeable and the resistance of the lightly doped junction region is increased. Moreover, the formation of salicide is disturbed by the narrow line effect, thereby leading to an increase in the resistance of a gate electrode. This causes a transistor operating signal of a semiconductor device to be distorted, which lowers the reliability of the semiconductor device.
Besides, new equipment should be used in order to change the type of metal layers. This makes the productivity of semiconductor devices decreased owing to the introduction of high-cost production facilities.